KR100883423B1 - Apparatus for drive control of LED in back light unit - Google Patents

Abstract

The present invention is to provide a drive control device of the LED backlight unit, LED array used as a light source of the TFT LCD; A sensor unit detecting a state of the LED array; A power control unit which receives a state of the LED array sensed by the sensor unit and supplies power to the LED array by preventing a sudden power change of the LED array; A constant current and pulse width control unit measuring the state of the LED array sensed by the sensor unit and informing the power control unit, and performing constant current and pulse width control on the LED array; And a power control unit for detecting a current of the LED array and informing the constant current and pulse width control unit and controlling a power device of the LED array based on an electric signal received from the constant current and pulse width control unit. Minimize the heat of LED used as the light source of LCD using on / off control, minimize the change of wavelength of output light, and control LED by analyzing the wavelength and quantity of light output from LED device.

LED, backlight unit, TFT LCD, drive control, constant current, pulse width

Description

Drive control unit of LED backlight unit {Apparatus for drive control of LED in back light unit}

1 is a block diagram of a driving control apparatus of an LED backlight unit according to an embodiment of the present invention.

2 is a block diagram showing a detailed configuration example of FIG.

FIG. 3 is a block diagram illustrating a power control unit and its peripheral blocks in FIG. 1.

FIG. 4 is a block diagram illustrating a constant current and pulse width controller and a peripheral block of FIG. 1.

FIG. 5 is a block diagram illustrating a power control unit and its peripheral blocks in FIG. 1.

Explanation of symbols on the main parts of the drawings

100: LED array 200: sensor unit

210: color sensor unit 220: temperature sensor unit

300: power control unit 310: commercial power

320: power protection unit 330: rectifier

340: monitoring unit 350: correction unit

360: step-up / decompression unit 361: first step-up / decompression unit

362: second boost / decompression unit 400: constant current and pulse width control unit

410: calibration correction 411: color sensor calibration

412: temperature sensor compensation 420: color sensor

430: pulse generator 440: pulse variable control unit

450: pulse width control unit 460: current detection correction unit

470: current control unit 500: power control unit

510: power device controller 520: current detector

530: power stabilizer

The present invention relates to a drive control apparatus for an LED (Light Emitting Diode) back light unit (BLU), and in particular, to heat the LED used as a light source of a TFT LCD (Thin Film Transistor Liquid Crystal Display), The present invention relates to a drive control device of an LED backlight unit which is minimized by using off control, minimizes a change in wavelength of output light, and is suitable for controlling an LED by analyzing the wavelength and amount of light output from the LED device.

In general, since the first light emitting diode (LED) device was first known in the world in 1907, technology evolution has been slowed down compared to other electronic devices. However, in the late twentieth century, LED has become a semiconductor light emitting device that is essential for human beings across the industry through breakthrough technology development and application of various applications. Experts expect LEDs to accelerate the development of these technologies. However, it is said that LED technology will mature successfully only with the development of LED technology, application fields expansion, and development of LED peripheral technology.

In the expansion of LED application field, LED is applied to various fields such as automobile, lighting, display, jewelry, toys, interior by applying high brightness and high reliability LED. On the other hand, if you look at the LED-related peripheral technology, you can see that the technology development is inferior to the development of application products.

For example, a general LED is known as a device that emits light when a DC (direct current, DC) 2.5 to 3.5V voltage is applied to the anode and cathode terminals of the LED device. However, in LED emitting phenomenon, the amount of light emitted from the device is determined by the amount of current supplied from the power source, that is, the number of electrons and holes.

For this reason, in order to drive an LED device that outputs a certain amount of light, an additional circuit is required to supply a certain amount of current to the device. When driving an LED device without using an additional circuit, the output light quantity decreases over time due to a change in the forward voltage (Vf) of the LED device. Moreover, when driving a combination of a plurality of LED devices having various characteristics than driving a single LED device, a more serious light quantity difference and durability difference between the devices are exhibited.

In order to solve this problem, it is essential to apply a CCC (Constant Current Control) circuit that does not change the current flowing by an external power supply or an internal load. Such a driving circuit is required to develop a lot of technology as a part that can give additional cost burden and difficulty in compact product development in product application.

Another related technical problem is the light quantity control portion of the LED device. Recently, in order to freely change the amount of light of LED, which is mainly used as an alternative light source, the amount of light is controlled by controlling the amount of current supplied to the LED of a single device. LED elements are driven in series and in parallel. In this case, reducing the total amount of current supplied to control the amount of light in LED devices will result in a difference in the turn-on voltage between the devices, resulting in devices that do not emit light, and intensified light differences between devices. Will get the result.

To solve this problem, we are trying to solve this problem by applying PWM (Pulse Width Modulation) driving method based on the characteristics of LED's high-speed operation. In order to apply the PWM type light quantity control circuit, complex circuits such as pulse generation, pulse width comparison, and modulator and expensive devices are required, and work to be combined with the aforementioned constant current driving circuit must be performed in parallel.

In addition to the above-mentioned technical challenges, the LED wavelength can be raised with a problem of changing the wavelength over time. Even if the light quantity control using the constant current control and the pulse width modulation is performed, the LED device having the semiconductor characteristics generates a change in the energy band gap that determines the characteristics of the spectrum according to the self-heating. The change of band gap causes output wavelength change (Phase Shift, color change) and gets worse depending on driving time and ambient temperature.

This characteristic of LED is pointed out as a big disadvantage in the application of LCD display device as a light source (LCD back light unit), which is one of the big axis of the LED light source application market.

In order to solve this problem, there is a method of minimizing heat generated from the LED by using on / off control, minimizing the change of wavelength of the output light, and using the color sensor and the wavelength of the light output from the LED device. Methods for minimizing the problems caused by analyzing the amount of light reflected in the LED control has been actively researched and developed.

As a semiconductor light emitting device, LEDs have many problems and technical problems to be considered in developing and manufacturing applications using the devices as well as advantages.

Therefore, the present invention has been proposed to solve the conventional problems as described above, and an object of the present invention is to minimize the heat of the LED used as the light source of the TFT LCD by using the on, off control and to minimize the wavelength change of the output light The present invention provides a drive control apparatus for an LED backlight unit that can control an LED by analyzing a wavelength and a light amount of light output from the LED device.

In order to achieve the above object, the drive control device of the LED backlight unit according to an embodiment of the present invention,

An LED array used as a light source of the TFT LCD; A sensor unit detecting a state of the LED array; A power control unit which receives a state of the LED array sensed by the sensor unit and supplies power to the LED array by preventing a sudden power change of the LED array; A constant current and pulse width control unit measuring the state of the LED array sensed by the sensor unit and informing the power control unit, and performing constant current and pulse width control on the LED array; And a power control unit for detecting a current of the LED array and informing the constant current and pulse width control unit and controlling a power device of the LED array based on an electrical signal received from the constant current and pulse width control unit. It is characterized by the configuration.

Hereinafter, an embodiment according to the present invention as described above, the technical spirit of the drive control device of the LED backlight unit will be described with reference to the drawings.

1 is a block diagram of a driving control apparatus of an LED backlight unit according to an embodiment of the present invention.

As shown here, an LED array 100 used as a light source of a TFT LCD; A sensor unit 200 for detecting a state of the LED array 100; The power control unit 300 receives the state of the LED array 100 sensed by the sensor unit 200 and prevents a sudden power change of the LED array 100 to supply power to the LED array 100. Wow; Constant current and pulse width control unit for measuring the state of the LED array 100 sensed by the sensor unit 200 to inform the power control unit 300, and performs the constant current and pulse width control for the LED array 100 400; The current of the LED array 100 is detected and notified to the constant current and pulse width controller 400, and the power device of the LED array 100 is based on an electric signal received from the constant current and pulse width controller 400. It characterized in that it comprises a; power control unit 500 for controlling.

The LED array 100 is characterized in that a plurality of LEDs are configured in a series, parallel or series parallel mixing.

2 is a block diagram showing a detailed configuration example of FIG.

As shown in the drawing, the sensor unit 200 is a color sensor unit for measuring three types of light of the red, green, and blue of the LED array 100 with an element including a photodiode or phototransistor and outputting it as an electrical signal. 210; And a temperature sensor unit 220 that monitors a temperature due to heat generated outside or inside the LED array 100.

FIG. 3 is a block diagram illustrating a power control unit and its peripheral blocks in FIG. 1.

As shown therein, a commercial power supply 310 for supplying power; A power protection unit 320 for preventing an overcurrent from the power supplied from the commercial power supply 310; Rectifier 330 for rectifying the power supplied from the power protection unit 320; A monitoring unit (340) for receiving a detection signal of the LED array (100) from the sensor unit (200) and monitoring the state of the LED array (100); A correction unit 350 which receives a current detection signal from the power control unit 500 and corrects a sudden power change of the LED array 100; Receives the rectified power from the rectifier 330, receives the state monitoring signal of the LED array 100 from the monitoring unit 340, the power of the LED array 100 from the correction unit 350 It is characterized in that it comprises a; boost / deceleration unit 360 for supplying power to the LED array 100 by receiving a change correction signal to boost or reduce.

The boost / decompress unit 360 receives the rectified power from the rectifier 330, and receives the state monitoring signal of the LED array 100 from the monitor 340 to boost or reduce the LED array. A first boost / decompression unit 361 for supplying power to 100; The second rectifier receives the power rectified from the rectifier 330, receives a power change correction signal of the LED array 100 from the corrector 350, and boosts or decompresses the power to supply power to the LED array 100. It is characterized in that it comprises a boost / decompression unit (362).

FIG. 4 is a block diagram illustrating a constant current and pulse width controller and a peripheral block of FIG. 1.

As shown in FIG. 2, the constant current and pulse width control unit 400 measures the state information of the LED array 100 sensed by the sensor unit 200 and outputs a correction value. )Wow; A pulse width control unit 450 which performs pulse width control by the value corrected by the measurement correction unit 410; A current detection correction unit (460) for outputting a correction value for the current of the LED array (100) detected by the power control unit (500); The current controller 470 receives a pulse controlled by the pulse width controller 450 and receives a value corrected by the current detection correction unit 460 to perform current control on the power device of the LED array 100. It characterized in that the configuration, including.

As shown in FIG. 4, the constant current and pulse width control unit 400 measures the state information of the LED array 100 sensed by the sensor unit 200 and outputs a correction value. )Wow; A reference frequency controller 420 for controlling and outputting a reference frequency; A pulse generator 430 for generating a pulse according to the reference frequency output from the reference frequency controller 420; A pulse variable controller 440 which performs variable control on the pulse; The pulse width which receives the pulse generated by the pulse generator 430, receives the pulse variable control of the pulse variable controller 440, and performs the pulse width control by the value corrected by the measurement correction unit 410. A controller 450; A current detection correction unit (460) for outputting a correction value for the current of the LED array (100) detected by the power control unit (500); The pulse array controller 450 receives the pulse controlled by the pulse width control unit 450, receives the value corrected by the current detection correction unit 460, and the LED array 100 by the value corrected by the measurement correction unit 410. Characterized in that it comprises a; current control unit 470 for performing a current control for the power device of the.

The measurement correction unit 410 corrects the light source control value of the LED array 100 from the color sensor unit 210 in the sensor unit 200 and transmits the color sensor correction unit to the pulse width control unit 450. 411; A temperature sensor correction unit 412 for receiving and monitoring a temperature sensing value of the LED array 100 from a temperature sensor unit 220 in the sensor unit 200 and transmitting a temperature correction signal to the current control unit 470; Characterized in that configured to include.

FIG. 5 is a block diagram illustrating a power control unit and its peripheral blocks in FIG. 1.

As shown in the figure, a power device control unit configured to determine a state of a power device of the LED array 100 and control the power device based on an electric signal received from the constant current and pulse width control unit 400 ( 510; A current detector 520 which detects a current of the LED array 100 through the power device controller 510 and transmits the current to the constant current and the pulse width controller 400; Receiving a control signal from the power control unit 300, the power stabilization unit for controlling the LED array 100 to minimize the effect of unstable power generated when controlling a high power light source for the LED array 100 ( 530); characterized in that comprises a.

The operation of the LED backlight unit driving control apparatus according to the present invention configured as described above will be described in detail with reference to the accompanying drawings.

First, the present invention aims to control the LED by minimizing the heat of the LED used as the light source of the TFT LCD by using the on / off control, minimizing the change of the wavelength of the output light, and analyzing the wavelength and the amount of light output from the LED device.

Therefore, in the present invention, in order to minimize all these problems in the LED BLU (Back Light Unit) driving control which is used as the light source of the TFT LCD, constant current control (Constant Current Control), PWM (Pulse Width Modulation, pulse width modulation) ) We propose LED BLU driving control system including power circuit suitable for LED BLU driving circuit with light quantity control, color sensor and temperature compensation function.

The system features a constant current control function to maintain a constant amount of light, a free amount control using PWM modulation, wavelength correction and color change correction using a color sensor, and a power supply circuit suitable for commercial voltages.

Based on the basic analog circuitry, the device features an easy-to-apply structure for microprocessors and integrated integrated circuits (ICs).

Each configuration of the present invention will be described in more detail as follows.

First, Figure 1 shows a schematic system schematic diagram proposed in the present invention. The system can be largely classified into an LED array 100, a sensor unit 200, a power control unit 300, a constant current and pulse width control unit 300, and a power control unit 500. This configuration is a system for controlling the optimal operation and to compensate for the problems caused in the LED BLU drive control implemented by combining a plurality of LED light source.

1.LED Array (100)

In the case of LED BLU, an LED element is used as a light source. However, the light quantity of the LED single product does not provide enough light that a BLU product should have. Therefore, a plurality of LEDs are used as a light source of the LED BLU by mixing in series, parallel, or parallel. The voltage and current values for lighting vary according to the arrangement between the LED and the array. The detailed specifications of the control system must be changed based on the specifications of the light source.

2. Sensor unit 200

The sensor unit 200 may be divided into a color sensor unit 210 and a temperature sensor unit 220.

The color sensor 210 is manufactured to measure three types of red, green, and blue light with photodiodes or phototransistors, respectively, and output the light as an electrical signal. The measured signal is reflected in the red, green, and blue light source control to monitor the LED BLU to output light of a certain color coordinate.

In addition, the temperature sensor unit 220 monitors the temperature of various points to prevent color changes and malfunctions due to heat generation from the outside or the inside, and signals to the power control unit 300 and the constant current and pulse width control unit 400. It serves to convey.

3. Power Supply

A part that supplies power for driving to the LED BLU system, and includes a boost / decompression unit 360 which is a circuit for depressurizing (Voltage Down Conversion) or Boosting (Voltage Up Conversion) according to the LED BLU specification. It has a structure to supply independent power to drive multiple channels with different colors or voltage specifications.

And to receive the input of the commercial power 310 through the power protection unit 320 to cut off the external noise or bad power, to convert AC (Alternating Current, AC) power to DC (Direct Current, DC) power The rectifier 330 is included.

The DC power converted by the rectifier 330 is supplied to the system through a boost / deceleration unit 360 that boosts or decompresses a power suitable for the LED BLU specification. At this time, the problem is solved by including a correction unit 350 reflecting the power flowing to the power supply in case of a sudden power change by the control of the LED BLU.

In addition, by adding a monitoring unit 340 for detecting the detection signal of the temperature sensor unit 320 and the over-current sensor serves to prevent the problem of over-current, sudden temperature rise that may occur in the power control unit 300 in advance.

4. Constant current and pulse width control unit 400

In the case of the LED light source, the output light amount is determined by the current, and constant current and PWM driving are essential for accurate light amount control. This operation is implemented as a combination of various electronic circuits, and the present invention will be described using only the proposed analog circuit.

The PWM driving method used to control the amount of light of the LED BLU has various methods, but the PWM driving control method proposed by the present invention is characterized by a simple circuit and easy variable control using an analog pulse generating circuit and a device.

In the operation of the circuit, the reference frequency controller 420 controls the reference frequency, and the pulse generator 430 generates a waveform having the reference operating frequency. In addition, a pulse waveform having a pulse duty ratio of 0 to 100% can be obtained in accordance with the reference level set by the pulse variable controller 440. The variable pulse signal thus made is controlled on / off by using the power device of the LED array 100 which is the LED BLU light source through the power control unit 300.

In addition, the controlled amount of power is fed back through the current detector 520 in the power control unit 500 and reflected in the current control so that a predetermined current flows in the LED BLU light source in a pulse form.

As another feature of the control circuit proposed by the present invention, the color sensor and the temperature sensor are mounted on the LED BLU to control the signals output from the sensor in consideration of the characteristics of the LED having a problem that the color or the luminance changes in the external temperature and the self-heating temperature. By reflecting in the LED BLU to ensure the operation reliability.

5. Power control unit 500

The power controller 500 is a power device controller 510 and a current detector for driving the LED or the LED array 100 used as a light source of the LED BLU based on the electrical signal received from the constant current and pulse width controller 400 ( 520).

In general, FETs (Field Effect Transistors) and transistors (Transistors) are mainly used as power devices. The type and allowable capacity of the device are determined by the amount of power flowing through the circuit. In addition, the power control unit 500 includes a current detector 520 by a resistor for detecting a current flowing in the light source, and the amount of current flowing through the circuit is measured using a voltage value across the resistor. ) Will be reflected. The resistive element in this role is determined by the capacity of the LED or LED array 100, and a high current element within several ohms is usually used.

The power stabilizer 530 included in the power controller 500 is a circuit applied for stable control while minimizing the influence of unstable power generated when controlling a high power light source using pulses. The element used in the power stabilization unit 530 is a zener diode, an inductance, a capacitor, and the like, and is applied in various combinations according to the type, structure, and specification of the LED BLU light source.

6. System features

This invention has the following features.

6.1 Stability

In the system proposed in the present invention, electronic circuits and devices are designed for analog operation, so the probability of malfunction is very low compared to digital control circuits. Furthermore, when controlling a large power LED BLU, the noise of the circuit generated by the PWM control and the resulting abnormal signal increase the probability of malfunction in the digital control circuit, and as a result of complicated circuits and costs to compensate for this problem, It leads.

6.2 Low Price Implementation

In the case of digital circuits, the cost of the device for implementing the circuit is expensive and the circuit is complicated. On the other hand, in the case of the analog circuit applied in the present invention, the price is lower and the life is longer than the digital device.

6.3 High speed operation

In the case of digital circuits and digital devices, there is a limit on the operating frequency. If the frequency is increased, the probability of malfunction is high and the cost of the device is increased. In contrast, analog circuits and devices applied in the present invention basically have a high operating frequency and a wide range of available devices.

6.4 Scalability

In the case of the constant current and the pulse width control unit 400, it is necessary to control the digital control element such as a microprocessor in the LED BLU which requires additional control. However, due to the nature of the control method that receives the analog input and then outputs the analog again, the sensor unit 200, the power control unit 300, and the power control unit 500 except for the digital processor element and some elements for digital control The circuit must be controlled in conjunction with the digital circuit. In view of these design conditions, the circuit proposed in this paper is easy to apply to various control circuits.

6.5 compatibility

The constant current control method used in the present invention is a circuit that allows a set current to flow in a circuit regardless of the capacity of the LED array 100 connected to the circuit according to a user's request. If the capacity is not exceeded, it can be used commonly for various LED BLU products.

As described above, the present invention minimizes the heat of the LED used as the light source of the TFT LCD by using on / off control, minimizes the change in the wavelength of the output light, and controls the LED by analyzing the wavelength and the amount of light output from the LED device.

As described above, the driving control apparatus of the LED backlight unit according to the present invention minimizes the heat of the LED used as the light source of the TFT LCD by using the on / off control, minimizes the change of the wavelength of the output light, The effect of controlling the LED by analyzing the wavelength and the amount of light will be effective.

Although the above has been described as being limited to the preferred embodiment of the present invention, the present invention is not limited thereto and various changes, modifications, and equivalents may be used. Therefore, the present invention can be applied by appropriately modifying the above embodiments, it will be obvious that such application also belongs to the scope of the present invention based on the technical idea described in the claims below.

Claims (9)

An LED array used as a light source of the TFT LCD; A sensor unit detecting a temperature and a light quantity state of the LED array; A power protection unit for receiving the temperature and light quantity state of the LED array sensed by the sensor unit, supplying power to the LED array, the commercial power for supplying power, and to prevent overcurrent in the power supplied from the commercial power And a rectifying unit for rectifying the power supplied from the power protection unit, a monitoring unit for receiving a sensed temperature signal of the LED array from the sensor unit and monitoring a temperature state of the LED array, and detecting current from the power control unit. A correction unit for correcting a sudden change in power of the LED array by receiving a signal and a rectified power source from the rectifying unit, receiving a sensed temperature signal of the LED array from the monitoring unit, and receiving the LED from the correction unit. The power supply is supplied to the LED array by boosting or depressing the power change correction signal of the array. A power control unit configured to include a boost / decompression unit; Measure the temperature and light quantity state of the LED array sensed by the sensor unit to inform the power control unit, and control the constant current and pulse width for the LED array, but the temperature and light quantity of the LED array detected by the sensor unit A measurement correction unit for measuring state information and outputting a correction value, a reference frequency controller for controlling and outputting a reference frequency, a pulse generator for generating pulses according to the reference frequency output from the reference frequency controller, A pulse variable controller for performing variable control, a pulse generated by the pulse generator, receiving pulse variable control of the pulse variable controller, and performing pulse width control by a value corrected by the measurement correction unit A current detection correction unit for outputting a width control unit and a correction value for the current of the LED array detected by the power control unit; A current that receives a pulse controlled by the pulse width control unit, receives a value corrected by the current detection correction unit, and performs current control on the power device of the LED array by the value corrected by the measurement correction unit. A constant current and pulse width control unit including a control unit; And a power control unit for detecting a current of the LED array and informing the constant current and pulse width control unit and controlling a power device of the LED array based on an electric signal received from the constant current and pulse width control unit. Driving control device of the LED backlight unit. The method according to claim 1, wherein the LED array, A drive control apparatus for an LED backlight unit, characterized in that a plurality of LEDs are configured in series, in parallel, or in parallel or in parallel. The method according to claim 1, The sensor unit, A color sensor unit measuring three types of light of the red, green, and blue light of the LED array with an element including a photodiode or a phototransistor and outputting the electrical signal; And a temperature sensor unit that monitors a temperature caused by heat generated from the outside or the inside of the LED array. delete delete delete delete delete delete

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